Art. 16. In addition to the prohibitions which shall be established by special conventions, it is forbidden: (1) To employ poison or poisoned weapons, or projectiles the sole object of which is the diffusion of asphyxiating or deleterious gases; (2) To employ arms, projectiles, or materials calculated to cause unnecessary suffering. Entering especially into this category are explosive projectiles or those charged with fulminating or inflammable materials, less than 400 grammes in weight, and bullets which expand or flatten easily in the human body, such as bullets with a hard envelope which does not cover the core entirely or is pierced with incisions.